More correctly, there have been many specially designed coronation crowns for incoming Monarchs some of whom who thought St. Edward's Crown was too heavy.
The old King vs Queen crown reference stems from the 1953 decision by QER II to change all Royal crests from the Tudor Crown to the St Edward's Crown. Therefore, it was/is referred to by many as the "King's crown" pre-1953 and "Queen's crown" post-1953. So it is possible that the next Monarch could choose any headdress they wish to adorn all Royal crests in the future. I recommend they choose one that pisses off the next generations of followers of heraldry and those serving under the resulting crests.